This invention relates to a method and a device for the production of security elements for electronic article surveillance as well as to a corresponding security element, one security element being comprised of at least two layers.
The goods in department stores and warehouses are being protected from theft increasingly by electronic devices. One way to guard against theft by electronic surveillance is to attach strip elements, meaning elongate soft magnetic pieces of metal (e.g., VITROVAC from the Vacuumschmelze company), to the goods. These strip elements trigger an alarm when present in corresponding monitoring systems, which are usually positioned in the exit area of the facility to be protected.
Electronic article surveillance can be described roughly as follows: A monitoring system has a transmitting device and a receiveing device. The transmitting device transmits an interrogating signal into a monitoring zone. This interrogating signal excites the strip element into transmitting a reply signal which is detected and identified by the receive device. The occurrence of a reply signal is equated with the unauthorized passing of an electronically protected article through the interrogation zone, and the alarm is triggered. An example of such a monitoring system is described in European Patent EP 0 123 586 A1.
Resonant security elements are used in addition to the strip-shaped security elements for electromagnetic article surveillance. These resonant security elements are comprised of a resonant circuit having capacitive and inductive elements. As soon as such a resonant circuit is exposed to a corresponding electromagnetic field insided an interrogation zone it transmits a reply signal with its resonant frequency.
It is an object of the present invention to provided a simple, economical method, a corresponding device and a web material manufactured by the method for the purposes of electronic article surveillance.
The object of the present with regard to the method is accomplished in that sections of a second web material cut to a predetermined length are conveyed in a direction transverse to the running direction of a first continuous material web and are applied to the first material web. An application example of web materials produced in this manner follows below.
The previously mentioned strip elements for electronic article surveillance come in a length of several centimeters (e.g., 3 cm). Labels, each containing one strip element, are conventionally provided in the form of a roll of labels and dispensed by means of suitable dispensing devices. Ifxe2x80x94as is usualxe2x80x94the strip elements measuring several centimeters in length are wound up in the longitudinal direction to a roll of labels, one roll of labels will contain relatively few labels. The picture is quite different, however, if the strip elements are wound up in the transverse direction to the dispensing direction. It is then possible to materially increase the number of strip elements per roll of labels.
The transverse arrangement of the strip elements affords particular advantages when it is considered how these strip elements are normally produced: A relatively wide soft magnetic endless strip is produced; this endless strip is subsequently split into several soft magnetic endless strips lying in side-by-side arrangement. A label applied from the side to the first material web thus contains several parallel strip elements. This way it is possible to achieve a further notable reduction in the production costs for label rolls containing strip elements.
According to a further application example, sections cut from a thin-film material are applied to an endless strip made of thin-film material (materials of this type are described in detail in European Patent EP 0 295 028). For production-related reasons, thin-film materials display a preferential direction, i.e., the reply signal is at its maximum level when the interrogation field is oriented parallel to this preferential direction but is at zero level when the angle of incidence is perpendicular to the preferential direction. If two layers of thin-film materials are arranged perpendicular to each other, the security element in question will always be excited into transmitting a reply signal regardless of its orientation in the interrogation zone.
The method of the present invention is characterized in that according to an advantageous further aspect the sections of predetermined length cut from the second material web can be applied to the first material web in steps or continuously. The advantage of the continuous method is, of course, the higher production rate.
The object of the present invention with regard to the device is accomplished in that a guide device is provided for a first material web, at least one dispensing device for feeding the sections of a predetermined length cut from a second material web is provided at right angles to the guide device, and a conveying device is provided to take successively from the dispensing device those sections of predetermined length cut from the second material web and affix them to the first material web either directly a side by side a or with a gap in between.
While in use of just a single dispensing device the sections are applied to the first material web in steps, with two or more dispensing devices a it is possible for the device of the present invention to work continuously. All that is necessary in this case is for there to be a certain distance between each of the n dispensing devices and for the sections to be fed at a rate coordinated with the running speed of the first material web. The rate at which the sections are fed has to be set at least high enough for a section to be in the correct xe2x80x9creadyxe2x80x9d position as soon as that area of the first material web is reached where the section is to be applied.
According to an advantageous further aspect of the device of the present invention, provision is made for the dispensing device to be a conveyor belt, for at least one electromagnet to be positioned in the inner space formed by the revolving conveyor belt, for at least one further electromagnet to be provided in the area underneath the first material web where the sections of the second material web are to be applied to the first material web, and for a control/regulating unit to be provided to switch the electromagnets on and off so that the sections of the second material web are applied to the first material web.
Furthermore, in accordance with a favorable embodiment of the device of the present invention the following is proposed: A stop or a sensor for detecting the correct position of the section of the second material web relative to the first material web is arranged in the end zone of the conveying device; the control/regulating unit switches the first electromagnet off and the second electromagnet on as soon as the stop or the sensor signals that the section of predetermined length cut from the second material web has reached the predetermined position relative to the first material web.
According to an advantageous further aspect of the device of the present invention, provision is made for n dispensing devices arranged at a relative distance of (2n+1)*(b+z), where b is the width of the sections of the second material web, and z the desired distance between two consecutive sections of the second material web. This embodiment permits the n dispensing devices to work parallel to each other, i.e., without time off-set. Obviously, the control effort is thus reduced considerably.
The advantages of a further aspect of the device of the present invention, which involve the setting of the running speed of the first material web so that the sections of predetermined length of the second material web are applied to the first material web in a continuous process, have already been mentioned in the foregoing.
Advantageously, provision is made for a take-up reel onto which the finished web material is wound.
The object of the present invention with regard to the security element is accomplished in that the first material web is a continuous material web to which the sections of a predetermined length cut from a second material web made of a magnetic material are conveyed in a direction transverse to the running direction (x) of the first material web and applied thereto.
Preferably, the first material web is a substrate; and sections of a predetermined length cut from the second material web are adhesive labels, each containing at least one security element for electronic article surveillance.
Alternatively, the security elements are a plurality of deactivatable or non-deactivatable strip elements arranged parallel to each other and in a direction transverse to the running direction (x) of the first material web.
A further embodiment of the security element of the present invention provides for the first material web to be a thin-film material whose preferential direction extends transverse or parallel to the running direction (x) of the first material web, and for the sections of predetermined length (x) cut from the second material web to be equally thin-film labels whose preferential direction extends respectively parallel or transverse to the running direction (x) of the first material web.
Similarly, it is possible for the sections of a predetermined length cut from the second material web to be resonant labels.